Is blood money obligatory for an amputated hand upon whoever assaulted a person by beating, even if the assaulted was an oppressor, and what is its value?

If the person struck is wronged, and the striker is an unjust aggressor, and the defender escalates his defense from the lightest means available, then he is not liable for any injury or its consequences. However, if he deviates from this, he is liable.

If it was possible to repel the assailant without injury, but an injury occurred, then he is liable, unless it was not possible. If it was possible to escape or get away, he is obligated to do so. Defending another is like defending oneself, in terms of permissibility and obligation, as long as one does not fear for one's own life. Killing an assailant in self-defense or similar situations incurs no liability or sin. Understanding the specifics of the situation requires a detailed inquiry, which is a matter for the judiciary.